1. Field of the Invention
The present invention relates to an actinic-ray- or radiation-sensitive resin composition, an actinic-ray- or radiation-sensitive film therefrom and a method of forming a pattern. More particularly, the present invention relates to an actinic-ray- or radiation-sensitive resin composition that is suitable for use in an ultramicrolithography process applicable to a process for manufacturing a super-LSI or a high-capacity microchip, a process for fabricating a nanoimprint mold, a process for producing a high-density information recording medium, etc., and other photofabrication processes, and relates to an actinic-ray- or radiation-sensitive film therefrom and a method of forming a pattern.
2. Description of the Related Art
Heretofore, the microfabrication by lithography using a photoresist composition is performed in the process for manufacturing semiconductor devices, such as an IC and an LSI. In recent years, the formation of an ultrafine pattern in the submicron region or quarter-micron region is increasingly required in accordance with the realization of high integration for integrated circuits. Accordingly, the trend of exposure wavelength toward a short wavelength, for example, from g-rays to i-rays and further to a KrF excimer laser light is seen. To now, an exposure equipment using an ArF excimer laser of 193 nm wavelength as a light source has been developed. Further, a method, known as a liquid-immersion method, in which the space between a projector lens and a sample is filled with a liquid of high refractive index (hereinafter also referred to as an “immersion liquid”) has progressed as a technology for enhancing the resolving power (see, for example, patent references 1 and 2). Still further, the development of lithography using electron beams, X-rays, EUV light or the like, besides the excimer laser light, is now being promoted.
Especially, the electron beam lithography is positioned as the next-generation or next-next-generation pattern forming technology. Resists of high sensitivity and high resolution are required for the lithography. Specifically, increasing the sensitivity is a very important task to be attained for the shortening of wafer processing time. However, the pursuit of increasing the sensitivity with respect to the resists for electron beams is likely to invite not only the lowering of resolving power but also the deterioration of line edge roughness. Thus, there is a strong demand for the development of resists that simultaneously satisfy these properties. Herein, the line edge roughness refers to the phenomenon that the edge at an interface of resist pattern and substrate is irregularly varied in the direction perpendicular to the line direction due to the characteristics of the resist, so that when the pattern is viewed from above, the pattern edge is observed uneven. This unevenness is transferred in the etching operation using the resist as a mask to thereby cause poor electrical properties resulting in poor yield. Especially in the ultrafine region of 0.25 μm or less, the line edge roughness is now an extremely important theme in which improvement is to be attained. High sensitivity is in a relationship of trade-off with favorable line edge roughness. How to simultaneously satisfy these is a critical issue.
It is now required to attain a decrease of film thickness in order to cope with the above-mentioned demand in recent years for the formation of an ultrafine pattern in the submicron region or quarter-micron region in accordance with the realization of high integration for integrated circuits. However, a deterioration of dry etching resistance attributed to the decrease of film thickness now becomes a problem. The current situation is that no full satisfaction is attained in this respect.
With respect to development defects as well, suppression thereof is demanded. How to simultaneously satisfy characteristics, such as high sensitivity, high resolution, favorable line edge roughness and favorable dry etching resistance, and suppression of development defects is a very important task.
The electron beam lithography utilized as a nanofabrication technology is now indispensable as a method of fabricating a photomask blank used in the production of a photomask for semiconductor manufacturing.